The Agent interface can be pretty simple to very complex depending on your use case,

most of how the Agents Interface interacts with the dialer will be via dispositions or just reacting to state changes from the dialer

, the more effectively it reacts to the dialers agent state changes the less issues you will have from agents trying to do things they shouldn't.

Limiting Agents

While this is very dependant on the use case, the principle is that you should limit the agent as much as possible:

If they are not in a running campaign:
- then they can't do anything
If they are in a running campaign:
- but are not Available (logged into the dialer)
  - then they only have the option to make themselves available to start receiving calls.
    - Button names:
      - Go Available
      - Start
      - Join Campaign
      - Next
      - Next Call
- and are busy on a call
  - then they should have the option to disposition the call (e.g. hangup, hangup & retry)
    - Button names:
      - Hangup Callee
      - Retry
      - Remove
- and are in wrapup state (a break period after a call where they can finish with admin)
  - then they should have the option to go available again to get the next call
    - Button names: (note how the names overlap with the initial available)
      - Go Available
      - Next
      - Next Call
- they should be able to make themselves offline for things like bathroom breaks.
  - Button names:
    - Log out
    - Leave Campaign

The Most Basic

At the most simple you only need the following:

Go Available: to change the agent into available state, which will allow them to login and to start receiving calls and exit wrapup state.
Hangup (with disposition C): to allow the agent to hangup the call without killing the conference and wasting time.

Possible Issues

An agent will stay in a conference call and get the callees automatically transferred in, having the agent hangup the call just means they have to re-login with the dialer and make themselves available again, and it wastes time.

Hide the Softphone or WebRTC softphone. Agents should not hangup the call until they want to exit the campaign.

In our experience agents keep making this mistake.

One of the biggest issues integrators have faced is the speed at which their DB can do lookups, since a notification is sent when an agent is connected to a callee and now their system has to take that reference and find all the related info to show the agent.
There are various strategies around this but the most effective is to use the preview notification to cache upcoming callee's information in batches.